1. The Field of the Invention
This invention relates to laminated documents such as I.D. cards and more particularly to security features for such documents.
2. Description of the Prior Art
Laminated documents such as I.D. cards essentially comprise a card or document usually containing information relating to the bearer and generally, a portion of the information is in the form of a photograph of the bearer. Normally, the card is protected by a plastic sheet material such as by lamination of the card to a plastic sheet material or, as is usually the case, by lamination of the card between plastic sheet materials. I.D. cards have many uses and their uses are increasing. For example, they may be used to establish a person's authorization to conduct certain activities (driver's licenses) or their authorization to have access to certain areas (employee I.D. cards) or their authorization to engage in credit transactions (I.D. credit cards). In view of their widespread uses, especially in commercial transactions, such as cashing checks, credit purchases, etc., it is important that the person relying on the I.D. card to identify the bearer have maximum assurance that the I.D. card has not been altered and/or that the I.D. card is not a counterfeit.
A great deal of ingenuity has been employed to provide this desired degree of assurance. For example, specialized adhesive systems and lamination techniques have been developed to prevent or discourage alteration of I.D. cards. These systems and techniques are designed to achieve a high degree of bonding efficiency between a surface of the card and any plastic sheet material bonded to it. Certain adhesive systems, for example, can provide what is known in the art as a "security seal". A "security seal" is best explained by describing what happens if an attempt is made to pull a plastic sheet material from the surface of a card bonded to the plastic. If a "security seal" exists, all or at least portions of the adhered surface will be removed from the card together with the plastic sheet material. Adhesives or adhesive systems which can provide "security seals" for I.D. card elements are described in such Patents as U.S. Pat. No. 3,582,439; U.S. Pat. No. 3,614,839 and in commonly assigned copending Applications Ser. No. 361,232 filed May 17, 1973 and Ser. No. 654,220 filed Feb. 2, 1976. All of these Patents and Applications are expressly incorporated here in their entirety.
Ideally, a "security seal" is designed to prevent alteration of or any further use of the card as well as any further use of the plastic adhered to it. Accordingly, a "security seal" is normally established between the information-bearing surface of the card or document and the plastic. Under such circumstances, removal of the plastic should also remove substantial portions of the information-bearing surface of the card to render the card unuseable for alteration purposes. Likewise, if extensive portions of the so removed information-bearing surface remain adhered to the plastic sheet material, the plastic cannot be reused without employing specialized techniques to remove the adhered portions. A "security seal" is considered to provide an excellent capability for preventing or effectively discouraging alteration of documents such as I.D. cards and they are employed extensively as a primary anti-alteration security feature in I.D. cards.
The counterfeiting of documents such as I.D. cards involving as it does the fabrication and issuance of I.D. cards by persons not authorized to do so presents additional and different security problems to the art. Perhaps the most effective way to prevent counterfeiting would involve strict control over the possession of the materials and equipment involved in the fabrication of I.D. cards. In most cases, however, this approach would be impractical and most likely impossible. For example, too many of the materials involved are commercially available and used in other applications. Instead, the art's response to the counterfeiting problem has involved the integration of "verification features" with I.D. cards to evidence their authenticity. The best known of these "verification features" involve signatures such as the signature of the one authorized to issue the I.D. card or the signature of the bearer. Other "verification features" have involved the use of watermarks, fluorescent materials, validation patterns or markings and polarizing stripes among others. These "verification features" are integrated with I.D. cards in various ways and they may be visible or invisible in the finished card. If invisible, they can be detected by viewing the feature under conditions which render it visible. Details relating to the use of "verification features" in I.D. cards can be found in such Patents as U.S. Pat. No. 2,984,030; U.S. Pat. No. 3,279,826; U.S. Pat. No. 3,332,775; U.S. Pat. No. 3,414,998; U.S. Pat. No. 3,675,948; U.S. Pat. No. 3,827,726 and U.S. Pat. No. 3,961,956.
All of the verification features discussed above have achieved a measure of success in preventing or discouraging counterfeiting. Duplication of these feature(s) apparently presents an obstacle or problem of sufficient difficulty to discourage would-be-counterfeiters. However, In certain respects, some features are considered to fall short in terms of the idealized performance characteristics desired. For example, signatures, validation marks or validation patterns may be duplicated by photographic techniques. Also, "verification features" involving fluorescent materials or polarizing stripes require that particular devices or conditions be available to detect the feature. Moreover, many of the features are expensive or specialized equipment, techniques or materials are required to install the feature in the finished card. In any event, there is a continuing need in the art for novel "verification features" which can provide laminated documents of improved overall security. This invention is addressed to that need and presents to the art improved laminated documents comprising a novel "verification feature" which closely conforms to the idealized performance characteristics desired for such features.